Grinding machine



July 16, 1929. H 5 I 1,721,309

GRINDING MACHINE Filed Jan. 2, 1926 2 Sheets-Sheet '1' 9/4117 Miller.

July 16, 1929. H, MILLER 1.721309 GRINDING MACHINE w b- "Eli" Qua/nu Patented July 15, 1929.

entrain stares HARRY Gr. MILLER, or DENVER, coLonAno, ASSIGNOR T MILLER SERVICE TOOL 00.,

artists error;

01? MILWAUKEE, WISCGNSEN, A CORPORATIDN OF WISCONSIN.,

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Application filed January 2, 1926. Serial No. 78,838.

My invention relates to improvements in grinding machines, more particularly for grinding milling cutters and cutters used in valve reseating operations.

The object of this invention, generally expressed, is to provide a machine of this class which shall be simple in construction, economical in cost, reliable, durable and efficient.

In machine work generally and in auto mobile repair shops in particular, it is fre quently necessary to employ cutters for the purpose of producing angularly' inclined seats for valves and other parts. Cutters of this type may be used for cutting any angle desired, but for automobile valve reseating operations are usually employed for cutting 15, $0, 15 and 60 degree angles. hen cutters of this type become dull, it is necessary to regrind them. The regrinding operation has heretofore been considered to be a very difficult one as each tooth has to be ground separately and with such accuracy that the corresponding points on all of the teeth will be exactly the same distance from the center. Each tooth must also be given the proper clearance so that it will be effective in its operation. In conical cutters of the type that I intend to grind on my improved machine the teeth come very close together at the end having the smallest diameter.-

This makes is necessary to exercise the utmost care in grinding in order to'obtain the desired clearance without striking the cutting edge of the adjacent tooth.

The improved grinding machine that forms the subject of this invention, briefly described, consists of a base member to which an electric motor has been attached. A grinding wheel of emery or other abradant material is supported on a bracket secured to the base and is rotated about an axis parallel with the axis of the motor, a belt or other suitable power transmitting means being employed to transmit power from the motor to the grinding wheel. An upwardly extending arm is supported by two spaced brackets or lugs that extend upwardly from the base. This arm is rotatable or oscillatable about an axis that lies in the plane of the grinding wheel and is also movable along said axis towards or away from the grinding wheel. The upper end of the arm has a flat disk like surface provided with an upwardly extending central pivot which is adapted to enter an opening in a member that carries several spindles for the reception and sup port of the cutters to be ground.

llaving thus briefly described the structure of my improved cutter grindingmachine, I will now proceed to describe the construction and mode of operation in detail, reference for this purpose being had to the accompanying drawings in which the preferred embodiment thereof has been-"illustrated and in which:

Fig. 1 is a top plan view of my improved machine showing the same adjusted for grinding a forty-five degree cutter;

Fi 2 is a section taken on line 2 2, Fig. 1;

Fig. 3 is a'section taken on line 33, Fig.

1; parts being shown in elevationy F a is a section taken on line l4l, Fig. 3, and shows the parts adjusted for a thirty degree cutter; V Fig. 5 is a section similar to that shown, in

t but shows the parts'adjusted for grinding a sixty degree cutter; and e I Fig. 6 is a section similar to those shown in Figs. i and 5, but showing the parts adjusted to grind a fifteen degree cutter.

Figure 7 is a detailview of the stop screw 32- and associated parts.

In thedrawings numeral 5 designates the base upon which is mounted and secured an electric motor 6. Also, mounted upon-the base is a frame member or bracket 7 which extends upwardly above the motor and in which is ournalled the shaft 8 upon which is mounted, so as to rotatetherewith, a grinding wheel 9 o femery, carborundum or any other suitable abradant. Secured to the motor shaft 10 so as to rotate therewith is-a pulley 11 which is relatively largeand connected by a belt 12 with the pulley 13 on the grinding wheel shaft 8. ll hen the motor operates the grinding wheel will be rotated at a high speed, Extending upwardly from the base member directly in front of the grinding wheel so as to be bisected bya'plane passing through the middle of this wheel are two lugs 14 and 15, the former of which has a cylindrical opening 16 whose central axis is when it is rotated it will move towards or away from the lug 14, as the case might be. A pivot or shaft 20 has one end provided with a cylindrical part 21 that fits into the open ing in' member 18 and extends entirely through this member in the manner shown in Fig. 3. The other end of shaft 20, which has been designated by numeral 22, is somewhat larger in diameter than the part 21 and has an axial opening 23. The tubular end 22 extends into the opening 16. A spring 25 has one end abutting the bottom of the opening 23 and the other the bottom of the opening 16. This spring is under compression and produces a force which tends to hold the shoulder 26 in contact with the inner end of the screw 18. It is now evident that by rotating the screw 18, the shaft 20 may be moved in the direction of its axis. The screw 18 moves the shaft 20 positively in one direction and the s ring 25 returns it. Directly underneath the s aft 20, the base 5 has an opening 27 whose function will hereinafter appear. An arm 28 has a hub portion 29 thatis provided with an opening of the proper diameter to receive the tubular part 22 and is clamped in position on the latter by means of the set screws 30. The length of the hub 29 is less than the distance between the adjacent surfaces of the lugs 14 and 15 and may therefore be moved in one direction or the other until its ends come into contact with the adjacent surface of one of the lugs 14 or 15. An arm 31 extends downwardly from the under side of the hub and terminates within the opening 27 A screw 32 extends through a threaded opening in this arm and serves as an adjustable stop which limits the extent of oscillation of the arm 28. The upper end of the arm 28 is provided with a flat circular part 33 whose upper surface is plane. A stud 34 projects upwardly from the center of the part 33 and extends perpendicularly witlr the upper surface thereof. A part that may be termed a turret head has a circular base 35, the lower side of which has an annular plane surface 36 that is adapted to rest upon the plane upper surface of the part 33. From the upper surface of member 35 a central cylindrical member 37 extends. This member has an axial opening 38 extending the entire distance from the lower surface of member 35 to the upper end of this member. This opening is of the proper size to receive the stud 34. The upper end of this opening is of somewhat smaller diameter than the lower may berotated. The part marked 41 has a cut 43 extending inwardly from one side and a cylindrical opening 44 which intersects the axlal opemng through which the screw 40 passes. A rod 45 extends through the opening 44 and has one side flattened slightly in the manner indicated by numeral 46. This flattened portion engages the screw 40 and serves to prevent the rod 45 from rotating.

Secured to the outer end of the rod 45 is a sprin wire 47 whose function will appear as the description proceeds. Extending out wardly from the vertical cylindrical part 37 are three cylindrical shafts or bearings A, B and C. It will be noticed that the shaft marked A is the only one that extends radi ally from the center of member 37. The other two bearings B and C are tangent to circles whose centers coincide with the center of the stud 34 and whose radii are different. The reason for this feature of the construction will be hereinafter explained. The support-- ing member 33 has a U-shaped clamp secured to its under side in the manner shown in Fig. The upper arm of thismember extends inwardly over the upper surface of the base 35 and is provided with a clamping screw 49. The base 35 has a notch 50 cut in its outer edge so that the upper end of the clamp 48 may be passed in applying and removing the rotatable turret member. A number of holes 51 are provided in the part 35 for the reception of a pin 52. This pin is adapted to engage one of the holes 51 and a similar hole in the lower member so as to positively align the two parts and hold them in position While the cutter is being ground. I

I will now describe the operation of grinding a cutter. Let us assume that it is desired to grind a forty-five degree cutter such as the one shown in Fig. 1 and designated. by the reference character A This cutter is put into place on the bearing A. If the hole in the cutter is larger than the bearing a bushing 53 is employed in the manner shown. The parts 33 and 35 are then rotated until the line marked 45 (Fig. 3) coincides with the zero line on the stationary member 33 after which the pin 52 is inserted into the opening 51 that is new aligned with the corresponding opening in the part 33, after which the screw 49 is tightened so as to clamp the parts firmly together. The axis of the shaft A will now make an angle of 45 with the axis about which the grinding wheel 9 rotates and since the arm 28 oscillates about an axis that lies parallel with the plane of rotation of the wheel 9, it is evident that every point in the cutter tooth will oscillate in a plane that is perpendicular to the plane of rotation of the wheel 9; therefore if the position of the cutter is adjusted by means of the screw 18 until the edge of a tooth comes into contact with the cutting surface and if the parts are then oscillated about the axis of the screw 13, the wheel 9 will cut a surface that makes fortyfive degrees with the axis of the cutter. The Wire 47 engages the front side of the teeth and holds the cutter in the proper position. One

requisite to exact work is that when the oscillatory arm 28 is in the vertical position, the plane that passes through the middle of the grinding wheel 9 shall bisect the tooth to be ground so that in the grinding, the arm 28 can swing the same angular distance to both sides of the vertical. In this way the surface that is ground will be more nearly perfect than if other conditions prevailed. In order to enable, this adjustment to be obtained with cutters of different angularity, the shafts or bearings B and C have their axes spaced from the axis about which they rotate.

In my improved machine, the bearings of the upright arm or column 37, whose axes all he in a plane cutting the axis of the column at right angles, are constructed for use with cutters'of different angularity and so as to bring each cutter into proper relation with the grinding wheel, by a resort to two expedients, one of which consists in varying the position of the axes of the different bearings with reference to the axis of the column, while the other consists in varying the distance of the shoulders of the different bearings from the center or axis of the column. In my improved machine both of these expedients are resorted to and by such a combination it is be lieved the best commercial results in a machine of this character may be obtained.

The ideal position for grinding cutters is to have the cutter in such relation with the grinding wheel that the central plane of rotation of the grinding wheel shall bisect the teeth of each cutter when the latter is in the normal or central grinding position, and the variation in the position of the axes of the bearings with reference to the axis of the column, and the variation in the distance of the shoulders of the various bearings from the center of the column are resorted towith this end in view.

Referring'now to Figure 6 in which the central plane of the grinding wheel does not bisect the tooth of the cutter as the structure is shown, I wish to call attention to the fact that if the shoulder of the collar 54 were made somewhat longer so that the cutter would be moved somewhat farther from the center of the column or arm 37, the teeth of the cutter shown in Figure 6 would be bisected by the central plane of the grinding wheel. In this case, of course, it'would be necessary through the instrumentality of the feed screw 18, to move the support awayfroni the grinding wheel in order that the cutter might be moved into such ideal grinding relation. This illustration indicates that the distance of the shoulders of the bearings from the center of the column is an important feature.

Let us now consider Fig. I where a thirty degree cutter C is shown. The axis of the hearing or shaft C, instead ofintersecting the axis of the part 37, passes to the right thereof so that-the central portion of the surface to be ground lies in the central" plane of the grinding wheel when'thearm 28is vertical.- The bearings A, B and C are provided with shoulders 53A, 53B and 53C, respectively which hold the cutters from sliding inwardly. In Fig. 6 I have shown a fifteen degree cutter secured to the bearing C. This has been accomplished by applying a collar 54'to the bearing. Similar collars may be provided whenever necessary for the purpose of bringing the cutter into the position necessary for obtaining the best results.

I will now explain how the proper'clearance is obtained and for this purpose reference willbe had more particularly to Fig. 3. In this figure the cutter hasbeen shown partly by dotted lines and partly by full lines. The tooth that is being ground has been designated by numeral 55. The horizontal line marked C passes through the center of the grinding wheel and the line 56 represents the trace of a plane that contains the axis of the bearing A. Ifthe lines C and 56 were on the same level, then the ground surface would be inclined slightly inwardly and forwardly with the result that there wouldbe no tendency for the teeth to out. By raising thelin e- 56 so that it will lie ashort distance above the center line C the cutting edge willbe glven the proper clearance. It is obvious, however, that if line. 56 were raised too far above C that the periphery of the wheel 9 would come into contact with the cutting edge of the tooth directly beneath. The machine is so constructed that with a grinding wheel of the maximum diameter, the desired clearance will be obtained without strikingthe cutting edge ofthenexttooth i In operating the device the cutteris first applied to the proper'bearing and the upper edge of one of the cutter teeth brought into contact with the end of the spring- 47. -By means of the screw 18 the cutter is moved towards the grinding wheel until it comes into contact-therewith so as to give the desired depth of cut. The arm 28 is then oscillated so as to cause the surface of the tooth to pass transversely of the cutting surface of the wheel 9 and back again; the cutter is then rotated one tooth and the operation repeated until each tooth has been ground. Inthis manner all of the teeth are ground exactly alike and the operationcan be quickly per formed. In practice the cutters are made with a few angles only, among which 15, 80, and 60 are the most prevalent, and if cutters having different angles are made'they are so rare as to be almost unknown, therefore, by means of my simple machine'it is safe to say that any cutter of usual size and shapecan be ground. By means of bushings such as 53 and 54, it is possible to make provision for handling cutters having any sized central opening and any length, The holes 51 and pins 52 make it possible to quickly and accurately adjust the parts to accommodate cutters having any of the usual angles. This machine is to a great extent a duplicate of the machine shown, described and claimed in my copending application, Serial No. 57,105, filed September 18, 1925, but differs from it by having incorporated therein means specifically intended for the support of cutters and it is to this modified construction that the claims presented herewith have been directed.

In the preceding parts of this specification reference has been made to 45, 30 and 60 degree cutters. In order to make it clear what is meant by this, applicant has indicated the sixty degree angle in Figure 5 by the letter W. These angles are the angles that the cutting edge of the teeth makes with a plane per- V pendicular to the axis of rotation of the cutters, and cutting said axis at right angles.

It will be noted that the pawl or stop 47 has no adjustment relative to its supporting rod 45. This simple matter has considerable bearin on the successful operation of my machine. In the grinding of cutters, it is essential that the angle that the cutting edge of the teeth makes with the axis of the cutter shall be accurate. With the arrangement of parts-shown and described in this application, this angle cannot be altered when the parts are once adjusted because the pawl, tooth or stop 47 is in a fixed position. As before explainedI obtain the desired clearance by-raising the center of the cutters above the horizontal center of the grinding wheel and providing the stop 47, which positively locks the cutting edge of the teeth ata predetermined level. If, for instance, the stop 47 could be adjusted, the operator might vary the clearance by varying this stop, but such variation would change the angle of the cut ter and thereby make it impossible to predetermine the setting of the machine soas to obtain the desired angle, for this angle depends on two variables, namely, the horizontal level of the cutting edge and the angular relationship of the axes of the cutter-supporting bearing and the plane of the grinding wheel. By so constructing my machine that the stop 47 cannot be adjusted, accurate results may be obtained by any unskilled operator, as the accuracy does not depend on the skill of the operator but is predetermined by the construction of the machine.

Having now described my invention What I claim as new is: V

1. A cutter grinder comprising a grinding wheel, a rotatably adjustable column mounted in suitable proximity to the wheel and provided with a plurality of bearings adapted to receive cutters of varying angles, the axes of the bearings lying in a plane perpendicular to the axis of rotation of the column, said axes being variably positioned with reference to the axis of the column, so that the respective cutters may be brought into proper relation with. the grinding wheel, and means for varying the distance between the grinding wheel and column to carry the work into and out of grinding position.

2. A grinding machine comprising a grinding wheel, a rotary support mounted in proximity to the wheel and movable bodily toward and away from the wheel, the said support carrying a column whose axis coincides with the axis of the support, the column being provided with a number of bearings disposed therearound and whose axes all lie in a plane perpendicular to the axis of the column, the said bearings being respectively adapted to re ceive cutters or varying angles, the axes of the bearings being so disposed that when the cutters are mounted thereon, each cutter may be brought into proper grinding relation with the wheel, the axes of the bearings, except one, being nonradial to the axis of the column.

3. The combination with a grinding wheel, of a support movable bodily toward'and away from the periphery of the grinding wheel and mounted to rotate about its own axis in a plane perpendicular to the plane of rotation of the wheel and to oscillate on an axis lying in a plane passing through the center of the wheel and cutting its axis at right angles, the support having a column whose axis coincides with that of thesupport, the column having bearings disposed therearound, whose axes all lie in a plane perpendicular to the axis of the column, the bearings being located at dif: ferent distances from the axis of the support, one in a line radial to said axis and others in lines nonradial thereto, whereby said bearings are adapted to receive cutters of varying angles, the axes of the bearings being so disposed that each cutter may be brought into grinding proximity to the wheel, the axes of he bearings, except one, being nonradial to the axis of the'column.

4. In a cutter grinder the combination of a grinding wheel, a rotatable support adjacent the wheel and movable bodily toward and away from the same, the said support being mounted to oscillate on an axis lying in a plane passing through the center of thegrinding wheel and cutting the axis of the wheel at right angles, the support having a turret-like column whose axis coincides with that of the support, the said column having bearings disposed therearound whose axes all lie in a plane cutting the axis of the column at right angles, the said bearings being adapted to receive cutters of varying angles, the axes of the bearings, except one, being nonradial to the axis of the column, and so disposed that each of the bearings may be moved into position to grind the cutter carried. thereby.

5. In a cutter grinder the combination with a grinding wheel of an arm mounted to oscillate on .an axis lying in a plane passing through the center of the grinding Wheel and cutting the axis of the Wheel at right angles, a

supportmounte'd to rotate about its own axis on the oscillatory arm, its plane of rotation being parallel to the axis of oscillation of the arm, the support being providedwith a column whose axis coincides with that of the support, the said column having bearings disposed therearound whose axes all lie in a plane perpendicular to the plane of rotation of the grinding wheel, the bearings being adapted to receive cutters of varying angles, the axes of the bearings being so disposed that each cutter carried thereby may be brought into grinding relation with the wheel, the axes of the bearings, except one, being nonl radial to the axis of the column.

6. In a grinder of the class described, the

combination of a grinding wheel, an oscillathe support and having bearings disposed therearound and adapted to receive cutters of varying angles, the axes of the bearings lying in a plane cutting the axis of the column at right angles, the axes of certain of the bearings being offset from the axis of the column so that the cutters may be successively brought into such relative position to the grinding wheel that the central plane of r0- tation of the wheel shall bisect the teeth of each cutter when the support and column are in. the upright position and means for moving the work into and out of contact with the grinding wheel.

7. In a grinder of the class described, the combination of a grinding wheel, a support adjacent to the wheel and movable bodily toward andaway from the periphery oi the Wheel in the central plane thereof and including a column in turn table connection with the support and adapted to be rotatably adjusted about an axis off-set from the plane of bodily movement of the support and parallel thereto, said column provided with work supporting bearing pins in a plane normal to said axis, the axes of certain of the bearings being in nonintersecting relation with the axis of the column, so that the different cutters may be successively brought into proper grinding relation with the wheel and so that the central plane of rotation of the latter shall normally bisect the teeth of the various cutters and means for moving the work into and out of contact with the grinding wheel.

8. In a grinder of the class described, the combination of a grinding wheel, a set of rotatably adjustable work supports mounted in suitable proximity to the wheel, their plane of rotation being normally perpendicular to i that of the wheel and above that of the wheel distances from the said axis so that the cutters of different size carried by the respective bearings may be successively brought into grinding relation with the wheel and means for moving the work into and out of contact with the grinding wheel.

9. A machine for grinding cutters, comprising, in combination, a base, a grinding wheel supported from the base and adapted to be rotated about anaxis located above said base, a motor secured to the base, means for transmitting power from the motor to the wheel for rotating the latter, an arm mounted for oscillation about an axis that lies below the axis of the grinding wheel and which lies in the plane oi rotation of said wheel, a turret head secured to the upper end of said arm, means for permitting said head to rotate about an axis perpendicular to the axis of oscillation of said arm, said turret head having a plurality of bearings extending outwardly in a plane perpendicular to said axis and means for clamping the. head against rotation. on the arm. A

10. A machine for sharpening'cutters, comprising, in combination, a rotatable grinding wheel, and means for supporting a cutter while being ground, said means comprising an oscillatory arm adapted to swing about an axis lying in the plane of rotation of the grinding wheel, a stud extending upwardly from said arm, a turret head rotatably secured to said stud, means for locking said head against rotation about said stud and bearings extending outwardly from said head, said bearings having their axes in a plane perpendicular to the axis of the stud, said bearings being each adapted to receive and support a cutter. f t

11. A machine for sharpening cutters, comprising, in'combination, a-rotatable grinding wheel, and means for supporting a'cutter while being ground, said means comprising an oscillatory arm adapted to swing about an axis lying in the plane of rotation of the grinding wheel, a stud extending upwardly from said arm, a turret head rotatably secured to said stud, means for locking said head against rotation about said stud, bearings extending outwardly from said head, said bearings having their axes in a plane per pendicular to the axis of the stud, said bearings being each adapted to receive and support a cutter and means for adjusting said arm towards and away from the periphery of means for rotating'said wheel, a supporting arm mounted for oscillation about an axis lying in the plane of rotation of said grinding wheel, a turret head secured to said arm,

said head being mounted for rotation about an axis that is perpendicular to the axis of oscillation ofsaid arm, a plurality of shafts extending outwardly from said head, said shafts having their axes in a plane perpendicular to the axis of rotation of said head, said plane lying above the axis of rotation of the grinding wheel whenthe plane is in its uppermost position, and means for moving said supporting arm towards and away from the grinding surface.

13. In a grinding machine for sharpening cutters, in combination, a grinding wheel, means "for rotating said wheel, a supporting arm mounted for oscillation about an axis lying, in the plane of rotation of said grinding wheel, a turret head secured to said arm, said head being mounted for rotation about an axisthat is perpendicular to the axis of oscillation of said arm, a plurality of shafts extending outwardly from said head, one of said shafts being radial to the axis of the head andthe others being respectively tangential to circles concentric with said axis and of differing diameters, said shafts lying in,a common plane parallel to and offset from a plane which includes the grinding wheelaxis when the supporting arm is at the center of its arc of oscillation, said arm being adjustable toward and away from thegrinding wheel and each of said shafts being adapted to support a cutter in position for contact with the grinding wheel.

14., In a machine for grinding rotary cutters, the combination with an oscillatory support, of a rotatably adjustable work holding turret mounted thereon, means for limiting the arc of oscillation of the support, a series of cutter mountings on the turret each having an axis in the same plane but angularly divergent from the others with only one of said axes corresponding .to a radius of the turret axis'and each adapted by turret adjustment to hold one type of cutter with the working edges of its blades in positions for successive registry with a single grinding line, and a grinding wheel having a transverse line of its periphery coinciding with said grinding line.

15. In a machine for grinding rotary cutters, the combination with an oscillatory support including a turn-table having its axis at one side of and parallel to a plane which includes the axis of oscillation, of a rotatably adjustable work holding turret supported from the turn-table for rotation about the axis thereof, means forrlimiting the arc of oscillation of the support, a series of cutter mountings on the turret some of which mountings have axes non-radial to the axis of the turret and each adapted by turret adjustment to hold one type of cutter with the working edges of its blades in positions for successive registry with a single grinding line, and a grinding wheel having a transverse line of its periphery coinciding with said grinding line in a plane which includes the axes of the cutters and which is parallel to a plane which includes the axis of said wheel.

16. In a machine for grinding rotarycutters, the combination with a grinding wheel, of a support mounted to oscillate in a plane parallel to the grinding wheel axis and across the central plane of the grinding wheel, a turret mounted upon said support with its axis parallel to said plane and ofi-set therefrom, said turret having a turn-table member provided with means for securely anchoring the turret to the support in different positions of rotative adjustment about said axis, said turret having shouldered projections eccentrically disposed, and provided with arms to support cutters, the blades of which differ in angular pitch, said arms being positioned to support their respective cutters, each with the working edges of its blades in position for successive registry with a transverse line in the periphery of the grinding wheel, when the cutter is rotatively adjusted thereon. v I

In testimony whereof I aflix my signature.

HARRY G. MILLER. 

